My vote is on autonomous electric cars and solar. While I have not taken the plunge on EV or Solar I’m watching both carefully and have a 3-5 year range in which I’ll probably do both. It is a tricky math question to determine rooftop solar needs without knowing the draw of the car(s). Autonomous is something I’m somewhat at the mercy of technology and the main benefit of traffic relief depends on mass acceptance, so that may come a little later but I see it as the people’s choice here. Ultimately it should eliminate traffic when fully implemented. Rail and busses will never work here unless something like a hyperloop with individual cabins can be developed. I’ve been on mass transit in many cities in the US and abroad and it will never work here because of our liberties, freedoms and rights. The homeless and mentally ill are not/rarely forcibly institutionalized here and I believe never will be again. It’s trending towards addicts not being incarcerated either. Those are your mass transit fellow riders. Plus germ phobia seems to get worse every year, people wipe down their shopping carts nowadays, at medical offices and hospitals people wear medical masks as self protection as opposed to the sick wearing them to prevent contagion. Sharing space/seats/air will not increase, it will decrease. It hasn’t hit air travel due to the costs being prohibitive for most and the live attendants instilling order. This isn’t a personal preference, it’s an observation.

I believe a friend of mine summed it up best when I told him that if we get autonomous cars you can drive to work and while at work your car can work as a driverless uber until you need to go home. Once you get home, it can go to work while you sleep. His response was, “no thanks, I don’t need some strangers boogers under my seat or some knuckleheads unwashed hands on my steering wheel after he scratched his balls, let alone 50 of them a day. I also don’t share my toothbrush or underwear while I’m not using them”

Home solar, EV cars and autonomous driving solves all the problems with mass transit at least within a few hundred miles and air can handle the long distances.